Magnesium is a mobile element. When crops suffer from magnesium deficiency, symptoms first appear on the middle and lower old leaves, which is the core sign to distinguish magnesium deficiency from other nutrient deficiencies. Growers can quickly judge by leaf performance.

Typical magnesium deficiency symptoms: interveinal chlorosis and yellowing of leaves, while veins remain green, forming a clear reticular mottled pattern. In severe cases, the yellowed area gradually expands, leaf edges scorch and necrotize, and eventually the whole leaf dries and falls off. Magnesium deficiency in solanaceous crops can also lead to slow fruit expansion, uneven coloring and reduced sugar content. In fruit trees, it causes small fruits, weak flavor and poor storage tolerance.

Magnesium deficiency is most likely to occur in the following scenarios: first, acidic sandy soils, where magnesium ions are easily leached and lost with rainwater. Second, long-term excessive application of potassium and nitrogen fertilizers, as potassium ions and ammonium ions will antagonize magnesium ion absorption. Third, high-value crops such as grapes, citrus, tomatoes, strawberries and cucumbers have high magnesium demand and continuous consumption from year-round planting. Fourth, in low-temperature and low-light seasons, root activity is weak and magnesium absorption efficiency drops sharply.

When crops show the above magnesium deficiency symptoms, priority should be given to foliar spraying of EDTA chelated magnesium, which can quickly correct the deficiency and avoid yield and quality losses.